PURPOSE: To obtain a cheap electromagnetic shielding sheet which is formed of shape memory alloy and high enough in electromagnetic shielding performance.

CONSTITUTION: An electromagnetic shielding sheet 1 of shape memory alloy is sandwiched in between flanges 2 and 3 and clamped together with the flanges 2 and 3 by screws 6. Furthermore, this device is equipped with an electromagnetic wave generator surrounded with a case 4 and the flanges 2 and 3. The sheet 1 is turned into an intrisically memorized shape provided with a rugged surface at an operating temperature, so that many bridges of metal are produced in gaps locally generated between the flanges 2 and 3 to prevent electromagnetic waves from leaking out of the contact surface between the sheet 1 and the flanges 2 and 3.